High Efficiency Primary and Secondary Bias Flyback Converter with Dual Outputs

摘要

This disclosure relates to flyback transformer-based power converters that are capable of providing multiple output voltage levels. With respect to USB-PD adapter design, the flyback converter's output may be changed from 12V to 20V—based on the charging device's request. By using a bias circuit that monitors an output voltage level of the flyback converter, a bias voltage for the bias circuit may be determined to improve efficiency of the flyback converter. Embodiments include a comparator, microcontroller or switches to compare output voltage levels and provide bias voltages to the bias circuit.

主权项

1. A power conversion circuit comprising:
a flyback transformer including a secondary side with a secondary winding and an auxiliary winding, the flyback transformer configured to generate each of an auxiliary winding voltage at the auxiliary winding and one of a first flyback output voltage and a second flyback output voltage at an output terminal of the flyback transformer, wherein the first flyback output voltage is less than the second flyback output voltage; and a secondary bias circuit coupled to the secondary side of the flyback transformer, the secondary bias circuit configured to use one of the first flyback output voltage and the auxiliary winding voltage as a bias voltage, the bias voltage configured to control one or more switches in the secondary bias circuit at a light load.